Hello,
I registered for free mollom support for my drupal site. I tried configuring Mollom for comment form and node:forum topic.
I enabled testing mode. Comment form works fine. Any comment with "Spam" text as input were filtered.
But for forum topic, it returns:

The spam filter installed on this site is currently unavailable. Per site policy, we are unable to accept new submissions until that problem is resolved. Please try resubmitting the form in a couple of minutes.

My testing with comment form goes through fine. I get "Your submission has triggered the spam filter and will not be accepted.".

But same is not the case with new forum topic / story form. Now I don't get this error message also: The spam filter installed on this site is currently unavailable. Per site policy, we are unable to accept new submissions until that problem is resolved. Please try resubmitting the form in a couple of minutes.

So was wondering whether mollom free server allows only certain support or got something to do with testing mode enabled test?.

@Sun: Thanks for the response.
I tried with the latest development snapshot with free mollom registration.
Enabled the testing mode. Configured for:
Comment: Comment form Text analysis (discard)
Node: Forum topic form Text analysis (discard) and
Node: Story form Text analysis (discard)

For all three cases Invariable of whether text has spam word or not, it shows
"To complete this form, please complete the word verification below."
Looks like my above issue of response for Forum topic, story form are fixed.

Query is: For text analysis (discard) configuration why word verification captcha is shown?.
And previously the behavior is if the text doesn't have any spam content it goes through fine and for spam related keyword it discards (Happened only for comment form). But now invariably it asks for word verification.

Did you enable the testing mode in the global module settings before testing this?

To me the behavior you describe sounds like testing mode was not enabled, in which case you can post pretty much anything and since "testing posts" are usually short and random, there's a high chance that Mollom is going to be unsure and asks for a CAPTCHA.

By enabling the testing mode, you can test the actual behavior for the different cases. Use the literal strings "spam", "ham", or "unsure" in a form field that is checked by text analysis to trigger the corresponding response and behavior. Note that CAPTCHAs only understand and react to the literal strings "correct" and "incorrect" in testing mode (ignoring the characters shown in the CAPTCHA image).